I. Field
The present aspects relate to wireless communication, and more particularly, to techniques for noise estimation, such as, but not limited to, physical random access channel (PRACH) noise estimation.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content, such as voice content, data content, and so on. Typical wireless communication systems can be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP2, High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), 3GPP long-term evolution (LTE), LTE Advanced (LTE-A), etc.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple mobile devices. Each mobile device can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations can be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth.
To effect wireless communications, a user equipment requests access to enter a wireless network by transmitting a wireless signal on an access channel of the wireless network. The wireless signal is received by a base station and analyzed to determine whether to grant the user equipment access to the wireless network (e.g., if the user equipment is associated with a valid subscription to the wireless network). In order to successfully receive and demodulate a received signal, the base station must separate the received signal from other transmitted signals and compare received signal strength to noise on the access channel, among other things. However, noise estimation can be difficult where the signal strength is relatively weak compared to the noise, where interference from other transmitters exists, or where other physical conditions such as signal scattering, high Doppler effects, or the like, are prevalent on the access channel. Accordingly, mechanisms for accurately estimating and removing noise are beneficial to successful wireless communication.